I suspect a lot of people want to get into growing their own fruit and veg but have little idea where to start or feel like they need some guidance before feeling like they have any kind of direction. I'm by no means an expert, only an enthusiast with a bit of experience behind her. But enthusiasm can get you off the blocks.
Here's my little guide of things to consider when starting out on your journey.

1. What do you want to eat? It sounds obvious but make sure you grow what you want to eat. It's an opportunity to grow things just for yourself so don't forget that treats like asparagus and rhubarb are possible. Don't just buy the first varieties you find, have a read and ensure they are the type you want, eg tomatoes come in all sort of shapes, sizes, colours and flavours so make sure you choose wisely.
2. Where will you be growing? Do you have a window box, raised bed, greenhouse, allotment, corner of the garden or conservatory? It's surprising what spaces can be made use of but make sure you are growing something suitable for the area. Don't forget to consider the soil or mix of compost you are growing in to. 
3. Growing from seed, plug or plant? You can start at any stage for some plants, though others like carrots and parsnips really only grow well when sown directly and aren't moved. There are benefits to each stage but often plugs or plants will be more expensive than seeds. 
4. When to start? Don't start too early! It's a false economy to jump the gun as germination will be delayed or risk the seeds rotting. You cannot force the conditions to be right. The ground will be dry enough and warm in it's own time. A late frost could wipe out tender growth so bide your time. 
5. What are the risks for your plants? Make sure you consider if they will need support, shelter, protection from pests, regular watering, feeding and pruning. 
6. When will the harvest take place? You don't want to miss out on the fruits of your labour so keep an eye on when the harvest will be.